Steam-engine valve



(No Model.) 4 Sheets-Sheet 2.

N. W. TWISS.

STEAM ENGINE VALVE.

No. 473,486. Patented Apr. 26, 1892.

witweooeafi V B07 GIT-0214213 (No Model.) 4 Sheets-Sheet 4. N. W. TWISS.STEAM ENGINE VALVE.

No; 473,486. Patented Apr. 26, 1892.

WITNESSES.-

A T FOR/V57.

g UNITED STATES PATENT OFFICE.

NELSON WV. TWISS, OF NEW V HAVEN, CONNECTICUT.

STEAM-ENGINE IALVE.

SPEGIFICATION forming part of Letters.Patent No. 473,486, dated April28, 1892.

Application filed June 27, 1891.

To wZZ whom it may concern.-

. valve to the cylindenport. Letters Patent of the United States No.212,285, granted to me February 11, 1879, are for valves of this class,upon which my present invention is animprovement, having for its objectto adapt the construction both of the main and cut-off valves to insurepractically-balanced steampressures upon them and to provide forlargesteam-openings relatively to the valves travel, all as hereinafter morefully described and claimed.

In the accompanying drawings, forming a part of this specification,Figure l is a side View of an engine provided with valves of the classembodying my improvements. Fig. 2

is a cross-sectional view through the valve,

and steam-chest at that end of the cylinder farthest from the crank, themain valve being represented wide open and in the position shown in Fig.1 and the cut-off valve also being open. Fig. 3 is a view correspondingto Fig. 2, but showing the main valve in closed position on the point ofopening and with the cut-off valve in the position in which it travelswith the main valve up to the point of cut-off. Fig. 4: shows parts ofthe valves and their drivers in side elevation. Figs. 5 and 6 are sideand end views of the main valve, showing the driving projections. Figs.'7 and 8 are side and end views of the cut-off valve, showing thedriving projection. Fig. 9 is an inner end view of the main-valvedriver, and Fig. 10 is an inner end view of the cut-offvalve driver.Fig. 11 is a sectional view similar to Fig. 2, but showing the cut-offvalve closed; and Fig. 12 is a horizontal section through the main valveand steam-chest on Serial No. 397,742. (No model.)

the line as, Fig. 11, the dotted lines a: and y therein denotingthesectional planes on which the Figs. 2 and 13 and Figs. 3 and 11 arerespectively taken. Fig. 13 showsa modification in which theexhaust-chambers arejoined by a lengthwise chamber beneath thesteamchamber.

Referring to the drawings, A in Fig. 1 designates an engine-cylinder,and B denotes the steam-chest beneath the cylinder, which is dividedinto the usual steam and exhaust compartments C and D, (shown in thesectional views, Figs. 2 and 11,) which represent the end of thecylinder farthest from the crank. At each end of the steam-chest is acircular horizontal transverse valve-chamber E, directly at the end ofthe steam-compartment C and adjacent to the exhaust-chamber D at the endof the cylinder, from which suitable pipe connections may be made to theatmosphere or the condenser, and, if desired, both of theexhaust-chambers may be joined by a lengthwise passage 6 6 beneath thesteam chest. The usual exhaustport F opens from the valve-chamber intothe said exhaust-chamber and the steam-port G provides communicationfrom the valve-chamber to the cylinder-space H. From thesteamcompartment steam is admitted to the valve-chamber through anopening 22 in the bottom thereof, as shown.

The main valve K is of annular cross-section, having a concentriccylindrical chamber 70' throughout for the reception of the cut-offvalve R, fitting and adapted to oscillate therein. Said main valve isformed with a passage or steam way S, opening into the chamber 70through suitable ports .9, which are not located diametrically oppositeeach other, but are arranged a little to one side of a diametral planethrough the valve. A port 3 opens from the said passage S to the outsideof the valve in position to coincide with the steamport G, opening intothe cylinder. An. exhaust-cavity T is provided on the side of the valveadjacent the end of the cylinder, which is adapted to cover or span theports G and F and form a communication from the cylinder-space H to theexhaust-compartment D. In the lower side of the valve a port oropensteam-compartment to the interior of the ing 33 is adapted to admitsteam from the valve, and said opening is divided into two parts by atransverse bridge U, midway the length of the valve. The cut-off valve Ris cylindrical and hollow and is fitted to oscillate in the chamber inthe main valve. Steam is admitted to its interior through an opening 44,corresponding to the openings and 22 in the main valve andvalve-chamber. Nearly-opposite steam-ports r are arranged thereinslightly to one side of a diametral plane through the valve and adaptedto correspond to the ports 8 in the main valve, so that both said portsmay open at once, for the purpose hereinafter described. Each main Valveis driven by a suitable driver it, provided with suitable projections 70engaging suitable projections l on the end of the valve, which driverhas a hollow stem is, extending out through the bonnet 70 of thevalve-chamber, and carries a crank which receives motion from theeccentric of the engine and suitable connections, the two valves beingcoupled together and oscillated as one plain slide-valve in the ordinaryand well-known manner, not requiring further description.

The cut-off valve is driven by means of a driver m having a stem m,journaled within the main-valve stem 70 and suitable projections mengaging a suitable projection or tongue m which is formed on the end ofthe valve, as shown in Figs. 7 and 8.

The cut-off valve may be actuated, by an ordinary eccentric or by anyother well-known means of driving cut-olf valves; but the operatingdevices here contemplated comprise the disengaging cut-off mechanismshown and described in Letters Patent of the United States granted to meFebruary 11, 1879, and numbered 212,285.

The cut-off mechanism forms no part of my present invention and need notbe here shown or further described, my present improvement relating tothe main and cut-off valves and valve-chambers.

In operation it will be seen that by means of the construction of theports 8 and their uniting-passages Sin the main valve and thecorresponding ports r in the cut-off valve a given amount of travel ofthe circumference of the cut-off valve provides twice that amount ofsteam-opening into the cylinderthat is, the motion of the valve isreduced just onehalf for a given amount of steam-opening compensate forwear.

and the cut-off will be twice as sharply effected as if a single openingof twice the width were employed, and the wear of the cut-oif valve willbe proportionately reduced. As the openings s in the main valve are setslightly to one side of a diametral plane therein, the cut-off valve istherefore nearly balanced, but with a sufficient excess of press ure onthe back thereof to keep the valve tight against its seat and alsoautomatically Thus while it is kept tight and firmly seated it ispractically balanced and will oscillate in its bearings with minimumfriction. The main valve is also sufficiently balanced by means of thedevices shown in Figs. 2, 5, and 6, which consist of two longitudinalbars a fitted loosely in corresponding grooves a in the valve on theside opposite from the exhaust-cavity, and segmental parts of circularrings a fitted in corresponding grooves a joining the ends of thelengthwise grooves, the said pieces being jointed together at theircorners and held tightly against the surface of the valve-chamber bysuitable springs a", together with steam-pressure underneath them, thusformin g a balancing area, from which steam-pressure is excluded, andany leakage of steam into said area is prevented from accumulatingpressure by a relief or drip passage a bored through the valve from thesaid area to the exhaust-cavity T through the bridge U. The said area isproportioned to practically balance the exhaust-cavity of the valve,

while insuring its being kept tight upon its seat, over the exhaust andsteam ports F G and automatically adjusted to compensate for wear.

I claim as my invention 1. In steam-enginevalves, the combination, withthe steam-chest having a cylindrical valve-chamber opening into thesteam-compartment and radial ports communicating, respectively, with theexhaust-compartments and steam-cylinder, of an oscillating annular mainvalve having an exteriorexhaust-cavity and steam-port conforming to theports of the valve-chamber, an openinginto the steamcompartment, apassage within extended circumferentially, its annular bodycommunicating with said steam-port, and interior multiports connectingsaid passage with the central concentric chamber, a hollow oscillatingcut-off valve fitting said central chamber and having ports opening fromits interior outward corresponding to the internal ports of said mainvalve, and a suitable opening adapted to receive steam from thesteam-compartment, and suitable drivers for operating the said valves,substantially as and for the purpose specified.

2. In steam-engines, the combination of the steam -chest provided withthe cylindrical valve-chamber having an opening into thesteam-compartment and radial ports communicating, respectively, with theexhaustcompartment and steam-cylinder, an oscillating annular main valvehaving an exterior exhaust-cavity and steam-port corresponding to theports of the valve-chamber, an opening for admitting steam into itscentral chamber, a passage S within its annular body communicating withthe external steam-port, and the interior ports 8, opening from thecentral chamber of the valve into said passage S nearly opposite eachother, but slightly off from a diametral plane through the valve,substantially as specified, an oscillating hol low cut-off valve fittingwithin the main valve and having an opening adapted to admit steam intoits interior from the steam-com- IIO partrnent, and nearly-balancedsteam-ports r slightly off from a diametral plane, as specified, andcorresponding to the ports 8 of the main valve, and suitable drivers orstems engaging and adapted to operate the said valves, substantially asspecified.

3. In combination, the steam-chest having a cylindrical valve-chamber Eat each end thereof, having the ports 22, F, and G, the annular mainvalve K, provided with the ports 33 T 8 passage S, and interior ports.9, the cut-off valve R, having the ports 44 and W, the main-valvedriver 7s, engaging the valve and provided with a hollow stem journaledin the bonnet of the valve-chamber, the cnt-ott-valve driver engagingthe cut-off valve and journaled in the hollow stem of the mainvalvedriver, and suitable levers or rock-arms secured on the ends of saiddriver and adapted to be operated by the valve connections of theengine, substantially as and for the purpose specified.

4. In a cylindrical oscillating steam-valve having steam and exhaustports, the combination of the longitudinal and segmental packing-barsfitted in grooves Within the valve and springs for expanding said bars,forming a balancing area opposite the exhaust cavity, and the valvehaving a drip or relief passage from said balancing area to theexhaust-cavity, substantially as and for the purpose specified.

' NELSON W. TWISS.

WVitnesses:

ANDREW J. HATCH, LEON F. BRoWER.

